diff --git a/lottery.py b/lottery.py
index cd198a4..bdbc228 100644
--- a/lottery.py
+++ b/lottery.py
@@ -129,7 +129,7 @@ def generate_final_seed(topic_info, winners_count):
             topic_info.created_at,
             ','.join([str(i) for i in topic_info.valid_post_ids]),
             ','.join([str(i) for i in topic_info.valid_post_numbers]),
-            ','.join(topic_info.valid_post_created),
+            ','.join([str(i) for i in topic_info.valid_post_created]),
         ]).encode('utf-8')
 
         md5_hash = hashlib.md5(seed_content).hexdigest()